Apparatus for the automated Handling of workpieces

ABSTRACT

An apparatus for the automated handling of workpieces comprising an object recognition device for detecting the workpiece and a gripper arranged at a gripping arm for picking the workpieces and a control for evaluating the data of the object recognition device, for track planning and for controlling the gripping arm and the gripper and comprising a compensation unit which allows an evasion movement of the gripper, wherein the compensation unit only allows an evasion movement of the gripper on the exceeding of a predefined first load of the gripping arm and remains rigid below the first load, wherein the first load is larger than a load exerted on the gripping arm solely by the gripper and/or the picked workpiece.

The present invention relates to an apparatus for the automated handlingof workpieces comprising an object recognition device for detecting theworkpieces and a gripper arranged in a gripping arm for picking theworkpieces and a control for evaluating the data of the objectrecognition device for track planning and for controlling the grippingarm and the gripper and comprising a compensation unit which allows anevasion movement of the gripper.

Such an apparatus for so-called “bin picking” is known from WO2010/024794 A1. In this apparatus, a resilient element is arrangedbetween the gripping arm and the gripper as a compensation unit whichallows a certain movement of the gripper on a load on the gripper due toa collision, for example. In this respect, a control is provided whichmeasures and/or controls the elastic deformation of this element.

The resilience of the element between the gripping arm and the gripperis in this respect intended to make it possible that on an inaccuratetraveling of the gripper toward a workpiece, the gripper is deflected onthe basis of the collision with the workpiece such that it can stillpick the workpiece. Only when a certain deformation of the resilientelement is exceeded should the picking procedure be stopped.

It is disadvantageous in this arrangement that a deformation of theresilient element not only takes place on a collision with aninterfering edge, but also due to the gripper's and/or the workpiece'sown weight so that the exact position of the gripper depends on thedeformation of the resilient element and can therefore only bedetermined with difficulty. The position of the gripper can in thisrespect in particular only be determined by an accurate measurement ofthe deformation of the resilient element. An exact monitoring of thedeformation is furthermore also necessary for the decision whether thepicking procedure should be stopped. In addition, the arrangement isprone to problems.

It is therefore the object of the present invention to provide animproved apparatus for the automated handling of workpieces.

This object is achieved in accordance with the invention by an apparatusin accordance with claim 1. Advantageous embodiments of the inventionform the subject of the dependent claims.

The apparatus in accordance with the invention for the automatedhandling of workpieces comprises an object recognition device fordetecting the workpieces, a gripper arranged at a gripping arm forpicking the workpieces and a control for evaluating the data of theobject recognition device, for track planning and for controlling thegripping arm and the gripper. The control can in this respect inparticular comprise an evaluation device for evaluating the data, atrack planning module for track planning and a control unit forcontrolling the gripper. A compensation unit is furthermore providedwhich allows an evasion movement of the gripper. In accordance with theinvention, the compensation unit, however, only allows an evasionmovement of the gripper on an exceeding of a predefined first load onthe gripping arm, while it remains rigid below the first load. Inaccordance with the invention, the first load is in this respect largerthan a load exerted on the gripping arm only by the gripper and/or bythe picked workpiece. In accordance with the present invention, inparticular no evasion movement of the compensation unit thus takes placedespite the load on the gripping arm by the gripper's and, whereapplicable, the workpiece's own weight.

It is therefore ensured by the compensation unit in accordance with theinvention and unlike by the resilient element used in the prior art thatthe gripper adopts a defined position with respect to the gripping armin normal operation. The position of the gripper in normal operation ishereby unambiguously defined so that a secure and accurate moving of thegripper via the gripping arm becomes possible.

The first load is in particular selected so high that this load limitcan only occur, at least in a travel position of the gripper, by acollision of the gripper with an interfering edge such as the workpieceto be picked and/or another workpiece and/or a side wall of a container.

The apparatus in accordance with the invention can in this respect inparticular serve the removal of workpieces randomly arranged in thecontainer since the position of the workpieces can be determined by asuitable object recognition device and therefore does not have to beknown in advance. The apparatus can naturally, however, also be usedwhen the workpieces are already present with a certain order in thecontainer.

In accordance with the invention, any desired system which allows theidentification of the workpieces and the selection of a workpiecesuitable for picking can be used as an object recognition device fordetecting the workpieces.

The detection of the workpieces in this respect typically comprises adata logging by a measurement process. An identification of theindividual workpieces in the detection zone from which a workpiecesuitable for picking is selected then takes place by evaluating thedata. The movement of the gripper or of the gripping arm moving it isplanned on the basis of the positional data of this workpiece. In thisrespect, a collision check can be carried out so that a movement routineis selected in which the gripper or the gripping arm does not collidewith interfering edges such as the other workpieces and/or the sidewalls of the container. The gripper or the gripping arm is thencontrolled using the data thus calculated.

In this respect, in particular optical sensors are used as the objectrecognition device, with in particular laser sensors and/or imagesensors being able to be used. The sensors can in this respect worktwo-dimensionally, two-and-half-dimensionally and three-dimensionally. A3D laser scanner is particularly preferably used in this respect.

A sensor arrangement is furthermore advantageously provided whichrecognizes an evasion movement of the compensation unit occurring due toa collision on an exceeding of the first load.

The sensor arrangement can in this respect, for example, comprise acontact sensor and/or an optical sensor.

Further advantageously, a predefined travel path of the gripping arm ispermitted on detecting a collision. The picking procedure is hereby notinterrupted, for example, when the gripper comes into contact with theworkpiece to be picked.

In this respect, the picking position of the gripper can be calculatedso that no direct contact usually arises between the gripper and theworkpiece by the traveling of the gripper toward the workpiece. Thestill permitted travel path in this case secures the system against anunnecessary stop if a collision does still occur, for example due toinaccuracies in the detection of the workpiece or in the control of thegripping arm.

Provision can alternatively be made that the picking position iscalculated so that a direct contact between the gripper and theworkpiece arises by the traveling of the gripper toward the workpiece.The detection of the collision thus allows a check as to whether thegripper was traveled into the correct position.

Provision can furthermore be made that the gripper is traveled toward aworkpiece for so long until a collision is detected.

Irrespective of the manner of the traveling of the gripper toward aworkpiece, the gripper can be moved back again after the picking up ofthe workpiece initially on the same path with which it was traveledtoward the workpiece. Since this path has not produced any collisions onthe traveling, the probability that no collisions will also arise on thetraveling back is particularly high in this respect.

Furthermore, in a possible embodiment, the data of the sensor of thecompensation unit can remain out of consideration for a certain travelpath on the lifting of the workpiece so that a deflection of thecompensation unit in this region is not evaluated as a collision. It canhereby in particular be avoided that dynamic and/or static loads on thepicking up of the workpiece, which result in a deflection of thecompensation unit, are erroneously evaluated as a collision.

Provision can furthermore be made in accordance with the invention thatindividual portions of the gripping arm movement are carried out atdifferent speeds. The gripping arm can in particular be traveled at alower speed in regions in which a collision has to be expected than inregions in which a collision does not have to be expected.

The gripping arm is in this respect advantageously traveled at a firstspeed for so long as the gripper is located outside the container forthe workpieces and at at least one second, lower speed for so long asthe gripper is located within the container. Further advantageously, thegripper is furthermore traveled at a third, still lower speed in a nearregion to the workpieces and/or interfering edges. The gripper can inthis respect in particular be traveled a certain path distance at thethird speed before a picking procedure takes place or before the gripperis traveled to the workpiece.

As already described above, the picking procedure does not have to bedirectly stopped in accordance with the invention when a compensationmovement of the compensation unit was detected. The picking procedurecan rather utilize the compensation path of the compensation unit inorder also to be able to carry out a further movement after thedetection of a compensation movement.

This compensation path can furthermore be utilized to brake the grippingarm in good time before the total compensation path of the compensationunit was used up despite corresponding processing times and controltimes.

The picking procedure is in this respect advantageously stopped andrestarted on the exceeding of a permitted travel path which correspondsto a second load of the gripping arm.

If, in contrast, it is detected that a collision is no longer presentbefore the permitted travel path was exceeded, the operation can becontinued without interruption.

In this respect, in accordance with the invention, the magnitude of theevasion movement does not have to be known to initiate a reaction to acollision. The travel path from the detection of the collision knownfrom the control of the gripping arm is rather utilized for thispurpose. A monitoring of the deformation of the compensation unit isthus not necessary in accordance with the invention.

The adjustment path of the gripping arm which the control allows afterthe detection of a collision is advantageously smaller than thecompensation path of the compensation unit. It is hereby ensured that ona movement of the gripping arm in the permitted adjustment region, theforces occurring by the collision are taken up by the compensation unit.

On the determination of the permitted travel path, the processing timeof the control and the reaction times of the drives of the gripping armscan be taken into account in this respect to ensure a braking in goodtime within the compensation path of the compensation unit.

The control in this respect advantageously has an overload functionwhich intervenes on the exceeding of a predefined third load of thegripping arm, with the third load being larger than the first and/orsecond loads. The overload function can in this respect in particular bethe overload function of a robot arm. Provision can furthermore be madethat the overload function works with reference to the monitoring of theload of the drives of the gripping arm. Provision can furthermore bemade that the overload function caries out an emergency stop onrecognition of an overload so that the gripping arm can only be releasedagain by a manual user intervention.

The compensation unit in accordance with the invention now prevents sucha high load acting on the gripping arm that the overload functionintervenes. In particular only a travel path is permitted on detectionof a compensation movement and thus of a collision of the gripper withan interfering edge by which the load does not increase beyond the firstload.

The gripper is advantageously moved back into a neutral position on theexceeding of the permitted travel path and the picking procedure isrestarted. In this respect, in particular a repeat detection of theworkpieces to be picked can take place before a workpiece is againpicked.

The traveling back of the gripper after the detection of a collision canin this respect first take place on the reverse path with which thegripper was moved up to the collision.

The sensor arrangement of the compensation unit can also be configuredsuch that the direction of a compensation movement is recognized. Thecontrol advantageously takes account of this direction of thecompensation movement thus recognized on the retraction of the gripper.It can in particular thus be prevented that the load of the gripping armincreases by the retraction.

The apparatus in accordance with the invention can furthermore have aforce torque sensor arrangement arranged separately from thecompensation unit at the gripping arm for measuring the load of thegripping arm. This combination of compensation unit and force torquesensor arrangement thus allows an exact monitoring of the load of thegripping arm and nevertheless ensures by the rigid design of thecompensation unit in accordance with the invention that a definedposition of the gripper is present at the gripping arm in normaloperation.

In a further embodiment, the apparatus in accordance with the inventioncan comprise two compensation units connected in series. This inparticular makes it possible to increase the compensation path providedby the compensation units.

The first compensation unit is in this respect advantageously acompensation unit having a spherical compensation movement, while thesecond compensation unit is a compensation unit having a linearcompensation movement. The protective function against loads in anydirections provided by the spherical compensation unit can hereby becombined with a large compensation path provided by the linearcompensation unit.

Provision can furthermore be made that the two compensation units arepreloaded via separate preload means. The loads at which the twocompensation units deflect can hereby be separately determined.

Provision can further preferably be made that the two compensation unitsdeflect at different loads of the gripping arm. Provision can in thisrespect in particular be made that the linear compensation unit onlydeflects when the spherical compensation unit has already previouslydeflected.

In this respect, the sensor arrangement which detects a deflection ofthe compensation unit is advantageously arranged at the compensationunit which deflects on the lower load of the gripping arm and/or at thecompensation unit having a spherical compensation movement.

The sensor unit for recognizing the deflection of the compensation unitcan further preferably only detect the deflection movement of one of thetwo compensation units, while a compensation movement of the othercompensation unit is not monitored.

In this respect, different possibilities result in dependence on theapplication for the configuration of the first load of the gripping armat which the compensation unit or, on the use of a plurality ofcompensation units, at which the first compensation unit deflects:

On the one hand, the compensation unit can be configured so that thefirst load at which it deflects is larger than the static loads whichare exerted on the compensation unit independently of the position andorientation of the gripper by the gripper as well as a by a workpiecearranged at the gripper. The compensation unit can optionally also beset so that dynamic loads, for example on the starting or acceleratingof the gripper, also do not result in a deflection of the compensationunit. It is hereby ensured that the compensation unit actually onlytriggers on collisions.

However, such a configuration is not always possible, in particular withheavy grippers and/or workpieces and/or with loads in normal operationwhich come relatively close to the maximum permitted load of thegripping arm.

Alternatively, the compensation unit can therefore also be configuredsuch that it admittedly remains rigid without a picked up workpieceindependently of the position and orientation of the gripper, butoptionally also deflects without a collision with a picked up workpieceand/or on dynamic loads.

The control of the apparatus in accordance with the invention is in thiscase preferably configured such that a deflection of the compensationunit is not necessarily evaluated as a collision. The control is furtherpreferably designed such that static loads of the gripper after thepicking up of the workpiece are reduced within a predefined travel path.

In this respect, the control can be designed so that the gripper changesthe orientation of the gripper after the picking up of a workpiece witha slanted gripper such that the static forces are reduced which areexerted on the compensation unit by the gripper's own weight and by theweight of the workpiece. The present invention in this respect makes useof the recognition that the maximum static forces on the compensationunit occur at a position of the gripper in which it is deflected to theside by 90° and becomes lower with smaller deflections with respect tothe vertical. An oblique orientation of the gripper can in this respectbe necessary on the picking up of the workpiece. After the lifting ofthe workpiece, however, it is possible as a rule to move the gripperback in the direction of the vertical to reduce the static loads.

The gripper is therefore advantageously directed downwardly into atravel position after the picking up of a workpiece and is in particularoriented in the vertical direction. The gripper in this respectadvantageously remains in the travel position during the travel pathwith which the workpiece is removed and placed down elsewhere.

The change in the orientation in this respect advantageously takes placeon the lifting of the workpiece. In this respect, in particular with anobliquely aligned gripper, the travel movement of the gripper on thelifting of the workpiece can correspond to the travel movement of thegripper toward the workpiece and can be superimposed with the pivotmovement by which the gripper is rotated in the travel position. In thisrespect, in particular the traveling toward the workpiece or the liftingof the workpiece takes place in the direction of the orientation of thegripper on picking.

Provision is advantageously made in this respect that the deflection ofthe compensation unit on the lifting is not evaluated as a collision. Itis hereby prevented that a deflection is erroneously evaluated as acollision due to the static and/or dynamic loads which arise on thelifting. In this respect, the signal of the sensor of the compensationunit in a certain travel region after the start of the lifting of theworkpiece is advantageously not taken into account.

In accordance with the invention, a compensation unit having twocompensation units connected in series, as was described above, isparticularly preferably used with a magnetic and/or pneumatic gripper.Such a compensation unit can, however, also be used with a mechanicalgripper.

In a further aspect, the present invention comprises an apparatus forthe automated removal of workpieces arranged in a container comprisingan object recognition device for detecting the workpieces and a gripperarranged at a gripping arm for picking and removing the workpieces fromthe container as well as a control for evaluating the data of the objectrecognition device, for track planning and for controlling the grippingarm and the gripper. In accordance with the invention, the gripper is amagnetic and/or pneumatic gripper in this respect.

This embodiment of the gripper in accordance with the invention has theadvantage that the gripper allows larger tolerances on the movement ofthe gripper into a picking position relative to the workpiece. In thisrespect, in particular a plurality of positions can be suitable forpicking a workpiece so that the workpieces can be picked more securely.

In this respect, an object recognition device can be used as the objectrecognition device for detecting the workpieces such as was alreadydescribed above with respect to the object recognition device fordetecting the workpieces in the previously described aspect of thepresent invention.

The evaluation of the data, identification and selection of theworkpieces, the track planning and the control of the gripper of thepositioning apparatus can also take place in a similar manner as hasbeen represented above with respect to the corresponding steps.

The object recognition device for detecting the workpieces in thecontainer is in this respect preferably arranged in its measurementposition above the container.

In the selection of the workpiece to be picked, it can in particular bedetected in this respect whether a workpiece was identified which can bepicked with a predefined first relative position between the workpieceand the gripper.

Such a first relative position can in particular represent an idealpicking position between the workpiece and the gripper which comprisesthe fact with a magnetic gripper, for example, that the magnetic surfaceof the gripper overlaps ideally with the workpiece.

However, the case can arise with parts not lying on one another in orderthan none of the workpieces present in the container can be picked withsuch a first relative position. In accordance with the invention, thecontrol can in this case select a workpiece which is picked with asecond picking position, for example a not ideal picking position. Witha magnetic gripper, for example, a certain offset can be allowed in thisrespect between the magnetic gripping surface and the workpiece. Apicking position rotated by an angle with respect to the ideal magneticpicking position can likewise be considered as an alternative pickingposition with the magnetic gripper, for example having an angle offsetof 90°. Alternatively, or also when this is not possible, a picking canbe attempted at the highest point of the workpiece, for example. Aplurality of alternative picking positions can in particular be providedwhich are used in the selection of the workpiece to be picked.

Provision can alternatively or additionally be made that the gripper iscontrolled in accordance with the invention such that for the case itcannot pick up a workpiece with a first position calculated for picking,it repeats the picking with a second, changed position.

Provision can in particular also be made here to pick a workpiece to bepicked with an offset or at its highest position when a sufficient covercannot be achieved between the gripping surface of the gripper and amain surface of the workpiece.

However, it cannot be ensured with a magnetic or pneumatic gripper thatthe gripper actually only picks up a single workpiece. The case can inparticular namely occur with the magnetic gripper that the gripper picksup two or even more workpieces.

The apparatus in accordance with the invention can furthermore have aforce torque sensor arrangement for measuring the load of the grippingarm. The force torque sensor arrangement can in this respect inparticular be arranged at the gripping arm separately from anabove-described compensation unit.

The control can in this respect recognize by an evaluation of the dataof the force torque sensor arrangement whether and how many workpiecescan be picked up. The weight of a workpiece or the loads exerted on theforce torque sensor arrangement in normal operation by this weight arein particular stored in the control for this purpose and can thus becompared with the loads actually occurring on the picking of aworkpiece. Alternatively, the determination whether and how manyworkpieces were picked up can also takes place by the monitoring of thegripping force and/or of the current or power required to operate thegripper, in particular with a magnetic gripper.

Provision can be made in this respect that the control reduces thegripping force of the gripper when, for example, it is recognized viathe data of the force torque sensor arrangement that more than oneworkpiece was picked up. The magnetic and/or pneumatic gripper also hasthe advantage in this respect that the gripping force can be setflexibly. In this respect, in particular with the pneumatic gripper, thepower of the griper electromagnet can be reduced. An attempt can be madeby the reduction of the gripping force in this respect to drop theexcess workpieces from the gripper again. In this respect, the grippingforce can advantageously be reduced for so long until it is recognizedwith reference to the data of the force torque sensor arrangement thatonly a certain number of workpieces, and preferably only one workpiece,was picked up at the gripper.

Furthermore, the picking procedure can in particular be repeated usingthe data of the force torque sensor arrangement when it is recognizedthat no workpiece was picked up on a picking procedure.

The apparatus in accordance with the just described second aspect of thepresent invention, in which a magnetic and/or pneumatic gripper is used,can in this respect preferably be combined with the first describedaspect of the present invention, i.e. with a compensation unit inaccordance with the invention.

The demands on the delivery accuracy or the gripper to a workpiece canhereby be kept small and the load of the gripping arm, which is unwantedon a collision which nevertheless occurs, and/or the necessity of amanual intervention can be avoided.

The two aspects of the present invention can in this case each be usedon their own or also combined with an apparatus in which the gripperremoves the workpieces from a container and places them on anintermediate station from where the workpieces are positioned moreaccurately and/or are singularized via a positioning apparatus. This isin particular of particular advantage when a magnetic and/or pneumaticgripper is used since it does not allow any accurate positioning of theworkpieces at a target receiver.

In this case, an embodiment is preferably used having two compensationunits connected in series, in particular a two-stage compensation unitsuch as was described above.

A gripper in accordance with the first aspect of the present inventionhaving a compensation unit in accordance with the invention can,however, also be used in accordance with the invention as a positioningapparatus for the more accurate positioning of a workpiece, startingfrom an intermediate station. In this respect, a mechanical gripper canin particular also be used.

In this case, an embodiment is preferably used having only onecompensation unit, in particular having a spherically workingcompensation unit such as was described above.

The workpiece can advantageously be removed from the container by afirst gripper and placed down on the intermediate station, with theworkpiece advantageously being dropped onto the intermediate stationfrom a certain height. A slanted plane can in particular be provided inthis respect onto which the workpieces are dropped. The workpieces canin this respect slide to a further transport position on this slantedplane.

Furthermore, a transport device can be provided on the intermediatestation which transports the workpieces from a placing region to aremoval region. The positioning apparatus advantageously removes theworkpieces in the removal region by the positioning apparatus in thisrespect, with a gripper, in particular a mechanical gripper,advantageously being provided for picking the workpieces in the removalregion.

In this respect, a repeat detection of the workpieces advantageouslytakes place on the intermediate station by which detection thepositioning apparatus, and in particular a gripper of the positioningapparatus, can be controlled. In this respect, in particular an objectrecognition device for detecting the workpieces is arranged in theremoval region.

In accordance with the invention, the workpieces can thus be placedrandomly arranged on the intermediate station and can nevertheless beaccurately picked due to the repeat detection.

The present invention furthermore comprises a compensation unit having abase unit and a compensation plate which is engaged around by a holdingregion of the base unit and is preloaded toward the base unit and inparticular the holding region via a spring arrangement so that thecompensation unit only allows an evasion movement between the base unitand the compensation plate on an exceeding of a predefined first loadand remains rigid under the first load.

Such a compensation unit can in this respect in particular be usedbetween a gripping arm and a gripper in accordance with the invention inorder, as described above, to prevent an overload of the gripping arm ona collision of the gripper with an interfering edge.

The compensation unit is in this respect preferably configured and isused as was described in more detail above with respect to theapparatus.

Further advantageously, one or more sensors are provided, in particularin the holding region, which monitor the lying of the compensation plateat the holding region. In this respect, it can, for example, be one ormore contact sensors and/or optical sensors. The sensors can thusrecognize whether the compensation unit carries out a compensation unitsince the first load was exceeded or whether the compensation unit isrigid. In this respect a plurality of sensors can preferably be providedso that the direction of the compensation movement can be recognized.

The compensation plate is round in a preferred embodiment. This allows acompensation movement in all directions by a slanted position of thecompensation plate. Further advantageously, a margin of the compensationplate is rounded to prevent a canting of the compensation plate.

Further advantageously, the compensation plate is arranged non-rotatablyat the base unit in order hereby to prevent rotational movements of thecompensation plate.

The movement between the base unit and the compensation unit can in thisrespect in particular allow a spherical compensation movement.

In a preferred embodiment, the compensation unit further comprises asecond compensation unit which allows a linear compensation movement.

Provision can be made in this respect that the two compensation unitsare preloaded via separate preload means. Provision can further be madethat the two compensation units deflect at different loads of thegripping arm.

The second compensation unit can in this respect in a possibleembodiment have one or more bars which are linearly guided in a guideand are preloaded via a spring.

In this respect, the spherical compensation unit and the linearcompensation unit are advantageously connected in series.

Further advantageously, the spherically working compensation unitdeflects first and only then the linearly acting compensation unit.

The present invention furthermore comprises a method for operating anapparatus for the automated handling of workpieces which has an objectrecognition device for detecting the workpieces and a gripper arrangedat a gripping arm for picking the workpieces as well as a control forevaluating the data of the object recognition device, for track planningand for controlling the gripper arm and the gripper as well as acompensation unit which only allows an evasion movement of the gripperon an exceeding of a first load of the gripping arm. In accordance withthe invention, the first load is in this respect selected larger thanthe forces occurring in the normal operation of the gripper, with thecompensation unit remaining rigid under the first load so that evasionmovements of the gripper are prevented in normal operation. The firstload can in this respect in particular be selected as larger than theload exerted on the gripping arm only by the gripper and/or by thepicked workpiece.

It is ensured by the method in accordance with the invention that innormal operation an unambiguous positional relationship is presentbetween the gripper and the gripping arm and evasion movements of thegripper only occur on a collision.

In this respect, in accordance with the method in accordance with theinvention a collision is advantageously recognized by the detection ofan evasion movement and the still permitted travel path on the detectionof a collision is restricted. If this travel path is also exceeded, thepicking procedure is stopped and restarted.

The method in accordance with the invention is advantageously carriedout in this respect as has already been described in more detail abovewith respect to the apparatus in accordance with the invention. Themethod in accordance with the invention in particular serves in thisrespect the operation of an apparatus as was described above.

Provision can furthermore be provided that the orientation of thegripper is changed after the picking up of a workpiece with a slantedgripper such that the static forces acting on the compensation unit dueto the gripper's own weight and the weight of the workpiece are reduced.The gripper is in this respect preferably oriented in a travel positioninto which it is oriented downwardly, and in particular downwardly in avertical direction.

The change in the orientation in this respect advantageously takes placeon the lifting of the workpiece. Further preferably, the deflection ofthe sensor on lifting is not evaluated as a collision.

The present invention further comprises a method for operating anapparatus for the automated removal of workpieces arranged in acontainer comprising an object recognition device for detecting theworkpieces and a gripper arranged at a gripping arm for picking andremoving the workpieces from the container as well as a control forevaluating the data of the object recognition device, for track planningand for controlling the gripping arm and the gripper. Provision is madein this respect in accordance with the invention that the workpieces arepicked magnetically and/or pneumatically.

The load of the gripping arm can advantageously be measured in thisrespect. Provision can in particular be made in this respect that thegripping force of the gripper is reduced when it is recognized that morethan one workpiece is picked up.

The method in accordance with the invention can furthermore take placeas has already been described above with respect to the apparatus inaccordance with the invention. The method in accordance with theinvention in particular serves in this respect the operation of anapparatus as was described above.

The present invention furthermore comprises a computer program forcarrying out one of the methods which were described above. The computerprogram in particular comprises commands for this purpose whichimplement the method on an apparatus for the automated handling ofworkpieces arranged randomly. The computer program in accordance withthe invention can in this respect in particular be used for implementinga control for an apparatus as was described above.

All the steps in the handling of the workpieces advantageously takeplace by the method in accordance with the invention and/or by theapparatus in accordance with the invention in a fully automated mannerand without a user intervention being necessary.

The subject of the present invention will now be described in moredetail with reference to embodiments and to drawings.

There are shown:

FIG. 1 a flowchart of a detection in accordance with the invention ofworkpieces and of a corresponding control of a gripper;

FIG. 2 a first embodiment of an apparatus which can be used for moving agripper in accordance with the invention;

FIG. 3 a second embodiment of an apparatus which can be used for movinga gripper in accordance with the invention;

FIG. 4 a first embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces randomly arranged in acontainer;

FIG. 4 a an alternative embodiment of a transport path as can be used onthe intermediate station in the embodiment shown in FIG. 4;

FIG. 5 a first gripper of the embodiment shown in FIG. 4;

FIG. 6 a detailed view of the gripper shown in FIG. 5;

FIG. 7 a second gripper of the embodiment shown in FIG. 4;

FIG. 8 an embodiment of a travelable object recognition device as can beused in the embodiment shown in FIG. 4;

FIG. 9 the travelable object recognition device shown in FIG. 8 in aside view;

FIG. 10 a second embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces randomly arranged in acontainer in which an embodiment of an intermediate station inaccordance with the invention having a revolving transport path is used;

FIG. 11 a third embodiment of an apparatus for the automated removal ofworkpieces randomly arranged in a container, which is based on theembodiment shown in FIG. 4 and which furthermore comprises an embodimentof a second intermediate station on which workpieces can be placed in atleast one receiver;

FIG. 12 the embodiment of a second intermediate station as is used inthe apparatus in accordance with FIG. 11 in a detailed view;

FIG. 13 a fourth embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces randomly arranged in acontainer, which is based on the embodiment shown in FIG. 4 and whichfurthermore comprises a second embodiment of a second intermediatestation on which workpieces can be placed in a receiver;

FIG. 14 a fifth embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces randomly arranged in acontainer which is based on the embodiment shown in FIG. 4 and whichfurthermore comprises a measuring device by means of which a measurementof the picking accuracy is possible;

FIG. 15 a detailed representation of an embodiment of a measuring devicein accordance with the invention in which the picking accuracy can bemeasured;

FIG. 16 an embodiment of a gripper in accordance with the invention witha stabilizer element;

FIG. 17 a sectional view through the embodiment of a gripper shown inFIG. 16;

FIG. 18 a first embodiment of a compensation unit in accordance with theinvention;

FIG. 19 a sectional view through the compensation unit shown in FIG. 18;

FIG. 20 a second embodiment of a compensation unit in accordance withthe invention,

FIG. 21 a front view of and a sectional view through the compensationunit shown in FIG. 20;

FIG. 22 a side view of the compensation unit shown in FIG. 20;

FIG. 23 a flowchart of a method for detecting workpieces in accordancewith the present invention;

FIG. 24 a flowchart of a method for the picking in accordance with theinvention of workpieces from a container; and

FIG. 25 a flowchart of a method for the picking in accordance with theinvention of workpieces from an intermediate station.

Embodiments of apparatus for the automated handling of workpieces willbe presented in the following in which the present invention is used.

The individual embodiments in this respect in particular serve the fullyautomatic singularization and/or positioning of workpieces. In thisrespect, any desired elements can be handled as workpieces, inparticular also asymmetrical workpieces beside workpieces with one ormore planes or symmetry or axes of symmetry. Furthermore, workpieces canbe handled in this respect which only have one gripping point orworkpieces having a plurality of gripping points. The apparatus inaccordance with the invention can in this respect in particular be usedfor handling metal workpieces. The workpieces can, however, naturallycomprise any desired materials and in particular also plastic. Theworkpieces can furthermore also comprise a plurality of materials, forexample a combination of plastic parts and metal parts.

In part in this respect, a gripper for picking the workpiece is combinedwith an object recognition device for detecting the workpieces so thatthe gripper can be controlled using the data determined by the objectrecognition device. Such apparatus in particular serve the automatedhandling of randomly arranged workpieces.

The object recognition device for detecting the workpieces can in thisrespect comprise any desired sensor whose data allow an objectrecognition of the workpieces. A laser scanner can in particular be usedin this respect. Alternatively or additionally, the object recognitiondevice can comprise one or more cameras. The object recognition devicein this respect preferably allows a 3D object recognition.Alternatively, however, a 2D or 2.5D object recognition is conceivable.

FIG. 1 shows the typical routine on the detection of randomly arrangedworkpieces and the corresponding control of a gripper. In step 1, ameasurement is carried out by the object recognition device by whichdata is obtained. These data are processed in a step 2 to allow anidentification of the individual workpieces in a step 3. Optionally, theobject recognition device can, however, also work using already knownpositional data of the workpieces.

In step 4, a workpiece which can be picked by the gripper is selectedfrom the identified workpieces. In step 5, the track for the gripper orfor the gripping arm moving the gripper is calculated using thepositional data of the selected workpiece. In step 6, this track is thenchecked for possible collisions with interfering edges to preventcollisions. If a collision-free track is found, it is used in step 7 forcontrolling the gripper, i.e. for traveling the gripper into a pickingposition toward the selected workpiece.

Such a method can in this respect always be used when a detection of theworkpieces and a corresponding control of a gripper take place inaccordance with the present invention.

The apparatus and methods in accordance with the invention can in thisrespect in particular serve the handling of randomly arranged workpiecessince the position of the workpieces can be determined by a suitableobject recognition device and therefore does not have to be known inadvance. The present invention can naturally, however, also be used whenthe workpieces are already arranged in a certain order.

Any desired apparatus having a plurality of axes of movement can be usedfor moving the gripper and the gripper can be moved on a defined trackand can be traveled toward the workpiece to be picked via the control ofsaid axes of movement.

In FIG. 2, a first embodiment of such an apparatus for moving a gripperis shown, with it being a multiaxial robot 10. It is in this respect asix-axial robot in the embodiment. It comprises a base 11 on which apedestal 12 is arranged rotatably about a vertical axis of rotation. Apivot arm is pivotably arranged about a horizontal pivot axis at thepedestal 12. A rotary arm 14 is arranged around a horizontal pivot axisat the pivot arm 13. The rotary arm 14 furthermore more has an axis ofrotation which allows a rotation about an axis of rotation arranged inparallel with the rotary arm 14. A gripping arm 15 is arranged around apivot axis arranged perpendicular to the axis of rotation of the rotaryarm 14 at the rotary arm 14. The gripping arm has an axis of rotationwhich stands perpendicular on the pivot axis. In accordance with theinvention, a gripper can be arranged at the gripping arm and can thus bemoved and pivoted in space via the control of the axes of movement ofthe robot.

In FIG. 3, an alternative embodiment for an apparatus for moving agripper is shown which can be used in all embodiments of the presentinvention instead of a robot. In this respect, it is a surface portalwhich has three linear axes of movement and is additionally equippedwith a further axis of rotation. In this respect, portal rails 21 areprovided at which a portal bar 22 is arranged in a linearly travelablemanner. A slide 23 is likewise arranged in a linearly travelable mannerat the portal bar 22. An arm is arranged travelable in the verticaldirection at the slide 23. This arm is additionally equipped with anaxis of rotation 25. The arm can in this respect have a gripper inaccordance with the present invention at its lower end.

In FIG. 4, a first embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces is shown whichcombines an object recognition device 30 for detecting the workpieceswith a first gripper 34 for picking the workpieces to remove theworkpieces arranged randomly in a container from the container using thefirst gripper 34. In this respect, the workpieces are not arrangeddirectly at a target receiver by the first gripper 34, but are ratherplaced down in a random arrangement on the intermediate station fromwhere they are positioned more accurately via a second gripper 41.

The embodiment in this respect has a receiver 31 for a container, notshown, with workpieces randomly arranged therein. Furthermore, achanneling in and channeling out device 32 can be provided for suchcontainers. The object recognition device 30 for detecting theworkpieces in the container is provided above the container, not shown.Its data are evaluated as initially described such that the workpiecesare gripped in the container via the first gripper 34 and can be removedfrom it. The first gripper 34 is in this respect moved via a robot 33 inthe embodiment. Alternatively, a surface portion can also be used here.

In the embodiment, a magnetic gripper is used as the first gripper 34since such a magnetic gripper makes less high demands on the deliveryaccuracy of the gripper to the workpiece and is therefore better suitedactually to empty containers 100% having workpieces which are arrangedchaotically in them and which moreover can be stacked over one anotherin random positions, as is possible in accordance with the embodiment ofthe present invention.

It is in particular possible with a magnetic gripper also to pickworkpieces having a non-ideal picking position. In this respect, acertain offset can in particular be present between the gripping surfaceof the magnetic gripper and a main surface of the workpiece. Inaddition, a picking is optionally also possible when the magneticgripper only engages at the highest point of a workpiece. If the controlcan therefore not identify any workpiece which can be ideally pickedusing the data of the object recognition device, that is with which anideal superimposition of the gripping surface and a main surface of theworkpiece is present, a picking with an offset or a picking at a highestpoint can alternatively be made use of. Such a picking can equally bemade use of when another picking strategy did not result in the pickingup of a part.

A pneumatic gripper could also be used alternatively to the magneticgripper 34. It is equally conceivable to replace the magnetic gripper 34shown in the embodiment in accordance with FIG. 4 by a mechanicalgripper if the workpieces are shaped such that they can also be reliablypicked in the container by a mechanical gripper.

The first object recognition device 30 can furthermore be used torecognize workpieces which arrived erroneously in the container. If aworkpiece is detected in this respect which does not satisfy therequired workpiece criteria and is therefore not to be positioned at atarget receiver, this can be separated out, for example in that theworkpiece is picked and is placed in a corresponding container.

In accordance with the embodiment, the workpieces are not arranged at atarget receiver by the first gripper, but are rather placed on anintermediate station from where they are picked up again by the secondgripper 41 and are then positioned more accurately. The placing down ofthe workpieces on the intermediate station can take place in a randomarrangement in this respect. The workpieces can in this respect inparticular be dropped by the gripper 34 from a predefined height onto aplacing region 35 of the intermediate station. The placing region 35 isin this respect configured as a sloping plane from which the workpiecesslide to a further transport zone.

The placing region 35 can have one or more height sensors whichdetermine the height of a workpiece arranged at the gripper 34 above theplacing region. In this respect, in particular a light barrierarrangement 37 can be provided which is arranged to the side of theslanted plane 35. If in this respect a workpiece arranged at the gripper34 arrives in the region of the light barrier arrangement, this meansthat the workpiece is arranged at a certain height above the slantedplane 35. The gripper 34 thereupon drops the workpiece. This procedurehas the advantage that the position of the workpieces at the gripper 34does not have to be exactly known. Collisions of the gripper with theplacing region are nevertheless prevented. Provision can in this respectin particular be made that the gripper 34 first moves in a horizontaldirection into a position above the placing region 35 after the pickingup of a workpiece from the container and then lowers it so far until thevertical sensor responds.

The intermediate station furthermore has a transport belt 38 whichtransports the workpieces from the placement region 35 on to a removalregion 44.

The workpieces in this respect slide from the slanted plane onto thetransport belt 38, with the slanted plan 35 being able to be bounded bylateral abutment regions 36 which narrow the slanted plane downwardly sothat the workpieces are directed to a defined further transport regionof the transport belt.

This further transport region is advantageously equipped with anoccupation sensor 39. It can in this respect in particular be a lightbarrier arrangement which determines the height of the workpieces placedon the transport belt. If a plurality of workpieces are stacked aboveone another, the occupation sensor responds. In this case, the furtherloading of the intermediation station by the first gripper 34 is stoppeduntil the occupation sensor again signals a sufficiently free furthertransport region.

The workpieces are transported on the transport belt 38 into the removalregion 44 and are there picked by the second gripper 41 to be positionedmore accurately or to be singularized. In this respect, a second objectrecognition device 42 is provided which detects the workpieces in theremoval region, with the second gripper 41 being controlled withreference to the data of the second object recognition device. A robot40 is in turn provided for moving the second gripper 41. Alternatively,a surface portal could also be made use of here.

The second object recognition device 42 is necessary for picking theworkpieces since they lie in a random arrangement on the intermediatestation or on the transport belt. The picking situation on theintermediate station is, however, substantially simpler than with thecontainer since the workpieces are all arranged in the same plane, i.e.on the transport belt, at least in the vertical direction. In addition,the workpieces are already presingularized and so can be picked moreeasily. In addition, the workpieces have a defined distance from theobject recognition device 42 so that it works more accurately.

The second object recognition device 42 can furthermore be used torecognize workpieces which arrived erroneously on the intermediatestation. If in this respect a workpiece is detected on the intermediatestation which does not satisfy the required workpiece criteria and istherefore not to be positioned at a target receiver, it can be separatedout, for example in that the workpiece is picked and is placed into acorresponding container or in that it is not picked and transported viathe transport belt further into a container.

Provision can be made in this respect that the second object recognitiondevice allows a more accurate detection of the workpieces than the firstobject recognition device so that incorrect workpieces are reliablyrecognized on the intermediate station.

In accordance with the invention, a mechanical gripper 41 can thereforebe used as the second gripper which admittedly makes higher demands onthe delivery of the gripper to the workpiece, but also allows asubstantially more exact picking and positioning of the workpieces. Inthe embodiment, the mechanical gripper is a finger gripper, inparticular a two-finger gripper such as will be presented later.

The control of the transport belt is in this respect in communicationwith the object recognition device 42 and the control of the gripper 41.In this respect, the transport belt stops in each case when a detectionof the workpieces and the following picking of a workpiece by thegripper 41 takes place. If, in contrast, there are no longer anyworkpieces in the removal region 44, the transport belt is moved onuntil workpieces are again located in the removal region 44. For thispurpose, a light barrier arranged laterally at the transport belt in theremoval region can optionally also be used for this purpose in additionto the data of the object recognition device.

The side walls of the transport belt 38 can be chamfered, as can berecognized in FIG. 4. It is hereby prevented that workpieces remain inunfavorable positions directly at the side wall which do not allow anypicking.

Provision can furthermore be made that a reorientation apparatus isprovided transversely over the transport belt 38 which flips overunfavorably arranged workpieces and thus brings them into a betterposition for picking by the second gripper 41. For example, a flap, notshown, or an abutment bar can be provided for this purpose which arearranged above the transport belt 38. Such a reorientation apparatus canin particular be arranged between the further transport belt 38 and theremoval region 44 of the transport belt.

In this respect, provision can be made in accordance with the inventionthat workpieces which cannot be picked at all by the gripper 41 fallinto a collection container arranged at the end of the transport path38. Alternatively, a peripheral transport belt 43 can be provided suchas will be described in more detail later.

Alternatively to the transport belt which is used as the transportdevice in FIG. 4, a number of other alternatives are available for theconfiguration of the transport device. The basic idea of theintermediate station is in this respect the design with a loading sideand an unloading side, a transport device between the two sides and afurther object recognition device over the removal side. The transportfrom one side to the other side can take place as follows, for example:

Driven transport device:

-   -   Linearly working transport device    -   Pusher, shuttle, slide, in particular driven by linear drives        such as a pneumatic cylinder    -   Transport belt    -   Circular    -   Round, segment table, circular store    -   Loop or circular belt    -   A plurality of planes above one another    -   From bottom to top    -   From top to bottom

Non-driven transport devices:

-   -   Slanted plane on which the workpieces slide down        Combination of the above-named driven transport devices and/or        non-driven transport devices

The position of the workpiece is preferably changed during the transportto increase the removal accuracy (place down inaccurately, removeaccurately). This can be achieved by end abutments, guide rails withchamfer, spring mechanisms, etc. The intermediate station canfurthermore also be used as a transfer picking site.

In this respect an alternative configuration of the transport device onthe intermediate station is shown in FIG. 4 a such as can be used in theembodiment shown in FIG. 4. In the upper region, the first gripper 33 isshown which picks the workpieces from the container and places them inthe placing region 38 on the intermediate station. In the lower region,the second gripper 40 is shown which removes the workpieces in theremoval region 44. The second object recognition device 42 isfurthermore shown which is arranged in the region of the removal region44.

In this respect a first transport plate 301 is provided as the transportdevice which can be traveled from the placing region 38 to the removalregion 44 and back via a linear drive 302 such as a pneumatic cylinder.In addition, a second transport plate 303 is provided which can likewisebe traveled from the placing region 38 to the removal region 44 and backvia the linear drive 304. The two transport plates and linear drives canbe configured identically in this respect. The two transport devices canfurthermore be arranged in parallel with one another. An empty transportplate is always available for loading or a filled transport plate forunloading through the embodiment with two transport plates so that thesystem can work without waiting times.

In FIGS. 5 and 6, an embodiment of a first gripper in accordance withthe invention is now shown again such as can in particular be used forpicking up the workpieces from a container. It is a magnetic gripper 34in this respect. In this respect, a magnetic gripping surface 47 isprovided at the lower side of the gripper. The magnetic gripper 34 inthis respect has an electromagnet which generates a magnetic force onthe magnetic gripping surface 47 for holding magnetizable objects.

The gripper in accordance with the invention is arranged cropped at theend member of the gripping arm, for example at the end member of thegripping arm of a robot 33. In this respect, a central axis of thegripper 34 or of the magnetic gripping surface 47 is arranged offset bya spacing 48 from an axis of rotation of the last pivot joint of thegripping arm. For this purpose, a cropped arm 45 is provided whichconnects the magnetic gripper 34 to the gripping arm. It is possible bythe cropped configuration of the gripper also to use it directly next toa side wall of the container in the interior of the container forpicking workpieces. It is thus in particular avoided that interferingedges further up at the gripping arm prevent a moving of the magneticgripper directly to a wall region of the container.

A compensation unit 46 such as will be described in more detail in thefollowing can furthermore be provided. This prevents an overload of thegripping arm from taking place on a collision of the gripper 34 withinterfering edges or with workpieces. In addition, it is prevented thata safety deactivation of the robot is activated which would only be ableto be bridged manually.

In FIG. 7, an embodiment of the second gripper 41 is shown which islikewise arranged at a gripping arm of a robot 40. In the embodiment, atwo-finger gripper having fingers 50 which can be traveled in a linearmanner is used as the gripper in this respect. The fingers can in thisrespect move into cut-outs of the correspondingly shaped workpieces andcan grip the workpiece by moving apart or moving together. Withdifferently shaped workpieces, other mechanical grippers can naturallyalso be used, in particular three-finger or multifinger grippers or bargrippers. A compensation unit 49 which protects the robot arm fromoverload on collisions is also provided in the embodiment shown in FIG.7.

FIG. 8 shows an embodiment of an object recognition device for detectingworkpieces which can be traveled from a position of rest into ameasuring position and back by a travel arrangement.

The object recognition device shown in FIG. 8 can in this respect inparticular be used in the embodiment shown in FIG. 4 as an objectrecognition device 30 for detecting the workpieces in a container. Thesecond object recognition device 42 used in the embodiment shown in FIG.4 for detecting the workpieces on the intermediate station is incontrast rigid in the embodiment. Alternatively, however, this objectrecognition device 42 could also have a travel arrangement to be able totravel from a position of rest into a measuring position and back.

The object recognition device shown in FIG. 8 has a sensor 30 whichdetects the workpieces. The sensor 30 is arranged at a sensor arm 52which is arranged in a travelable manner at a guide rail 54. The guiderail 54 is in turn arranged at a mounting bar 51 in order to thus beable to mount the fastening pieces 55 on a pedestal. The exactarrangement of the two pedestal columns can be recognized in FIG. 4.

In the embodiment shown in FIG. 4, the object recognition device is inthis respect arranged on pedestal columns such that the containers canbe led between the pedestal columns on the channeling into a removalposition.

As can be recognized in FIGS. 8 and 9, the sensor 30 can be traveledalong the guide rail 54 by moving the sensor arm 52. In the embodiment,the object recognition device is structured in this respect such thatthe sensor 30 can be traveled in a horizontal direction.

In the position of rest, the object recognition device is locatedoutside a collision region with the first gripper 34 so that it has freeaccess to the container. The sensor 30 is then traveled over thecontainer by traveling out the sensor arm 52 into the measuring positionin which the detection of the workpieces takes place for detecting theworkpieces in the container. In its measuring position, the sensor 30 islocated approximately centrally above the container. After themeasurement, the sensor is again moved back into the position of rest inwhich it is arranged outside the base surface of the container.

In this respect, the movements of the object recognition device and ofthe removal gripper 35 are synchronized with one another so that thedetection of the workpieces in the container always takes place when thegripper 34 places a workpiece on the intermediate station. The objectrecognition device is then traveled back into the position of rest sothat the gripper 34 can remove a new workpiece from the container. Inthe following placing of the workpiece on the intermediate station, ameasurement in turn takes place.

A similar procedure would in this respect also be conceivable with thesecond object recognition device 42 and the second gripper 41.

Alternatively or additionally, the object recognition device could alsobe traveled in the vertical direction. On the one hand, such a verticaltravel capability could be used in the same way as the horizontal travelcapability to move the sensor out of a collision region with the gripperwhen the latter picks up a workpiece and to move it closer toward theworkpieces again to carry out a detection. In addition, it would beconceivable to track the object recognition device in a verticaldirection with an emptying filling level of the container so that theobject recognition device is always arranged in an unchanging distanceregion from the workpieces arranged the highest in the container in themeasurement. A constant detection quality can hereby be achieved.

In the embodiment, a laser scanner can be used as a sensor of the objectrecognition device. The scanner can in this respect transmit a pluralityof laser beams at small intervals so that a fan of laser beams iscreated. The fan formed by the laser beams is then pivoted over thedetection region by pivoting the sensor, whereby a spatial detection ofthe detection region takes place. Geometrical data are created in thisrespect by distance measurement using the laser beams.

An arrangement of the sensor approximately centrally above the containerin this respect has the advantage that the side walls of the containerdo not form shadows. The travel capability of the sensor in this respectmakes it possible to position the sensor in the measuring position at asufficiently small distance from the workpieces to be measured andnevertheless not to come into conflict with the gripper or with thegripper arm moving the gripper. This is in particular of specialimportance when detecting the workpieces in the container since thescanner has to be positioned so low above the container, at least whenit cannot be traveled vertically, that it still detects workpieces withsufficient accuracy with an almost emptied container.

In FIG. 10, a further embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces from a container isshown which is based on the embodiment shown in FIG. 4 and in which theperipheral transport path of the intermediate station is provided whichis only indicated schematically in FIG. 4. Except for the differentlyconfigured intermediate station, all the components in this respectcorrespond to the embodiment shown in FIG. 4 so that reference is madeto the description there with regard to the total design of theapparatus.

The intermediate station also has a first transport belt 38 in theembodiment shown in FIG. 10, which transport belt transports workpiecesplaced in a placing region 35 to a removal region 44. The workpieces arethere detected by the object recognition device 42 and are picked andremoved by the gripper 41 which is moved by the gripping arm 40.

In accordance with the invention, the intermediate station shown in FIG.10 is now equipped with a return path 60 which allows workpieces notremoved in the removal region 44 to run around. The return path 60 is inthis respect likewise a transport belt which is arranged next to thefirst transport belt 38 and is moved in the opposite direction. Thereturn path 60 in this respect ensures that workpieces not removed inthe removal region 44 are transported back and again arrive on the firsttransport belt 38 so that they again move into the removal region 44where they can again be detected and picked.

If therefore a workpieces on its first detection lies at such a positionin the removal region 44 that it cannot be picked or can only be pickedwith difficulty, the control can dispense with a picking attempt and canallow the workpiece to run around. The circulation path is in thisrespect designed such that the workpiece is very highly likely to arrivein the removal region 44 in a different position on the next circulationso that there is a high probability that the workpiece lies in aposition which can be picked more easily on the second attempt.Workpieces with which an unsuccessful picking attempt was made can alsobe treated in the same way.

The removal region could also be arranged in the region of the returnpath in the embodiment shown in FIG. 10 without the function of theintermediate station changing.

Since the workpieces lie randomly arranged on the transport belts 38 and60, the probability is very high that they change their position on thecirculation. This can be assisted by further measures in accordance withthe invention. An abutment 61 is thus provided, for example, whichextends obliquely over the first transport belt 38 and forces theworkpieces from the first transport belt 38 onto the return path 60. Inthe same way, an abutment 62 is provided at the end of the return path60 which conveys the workpiece back onto the first transport path 38again. In this respect, a positional change of the workpieces iseffected solely by the contact with the abutments and the forcing ontothe respective other belt.

Provision can furthermore be made that the workpieces run through avertical difference during the circulation. A slanted plane or an edgehaving a vertical difference can in particular be provided in thisrespect over which the workpieces are forced. A position change is alsohereby effected. At the same time, workpieces caught up with one anothercan optionally be separated from one another.

In this respect, a slanted plane which the workpieces slide down isadvantageously provided in the transition region between the firsttransport belt 38 and the return path 60. The first transport path 38 inthis respect advantageously extends in the vertical direction, whereasthe return path 60 is arranged obliquely so that a vertical differenceresults in at least one of the two end regions of the two transportpaths.

To prevent parts which cannot be picked from remaining on thecirculation path for an unlimited time, a separation mode can beprovided in which the circulation is ended under certain conditions andthe workpieces are emptied into a collection container 63. The abutment61 can in particular be moved for this purpose such that the workpiecesare transported via the first transport path 38 up to its end and intothe container 63 placed there.

In this respect, in particular a separation mode can be provided inwhich no new workpieces are placed onto the intermediate station by thefirst gripper. At least one picking attempt then takes place with allthe workplaces located on the intermediate station. In this respect, aplurality of circulations can optionally also be carried out. Theworkpieces then remaining on the intermediate station can then beemptied into the container 63. It is thereupon in turn possible toswitch into the normal mode.

The separation mode can furthermore be used to separate out workpieceswhich erroneously arrived on the intermediate station. The separationmode can thus be activated when a workpiece was detected on theintermediate station which does not satisfy the demanded workpiececriteria and is therefore not to be positioned at a target receiver.

In the embodiment of an intermediate station shown in FIG. 10, thereorientation device 64 is also shown which was already described withregard to the embodiment in FIG. 4, but which was not shown there. Inthis respect, it is a flap which is arranged above the first transportbelt 38 between the placing region and the removal region. The flap 64should in this respect in particular flip over workpieces standing ontheir edge to make them easier to pick.

In FIG. 11, a further embodiment of an apparatus in accordance with theinvention for the automated removal of workpieces arranged in acontainer is shown. This embodiment is also based on the embodimentshown in FIG. 4 so that reference is first made to the description ofthe embodiment shown in FIG. 4 with respect to the configuration.

On the one hand, the channeling in and out for containers withworkpieces is shown which is only shown schematically in FIG. 4. Theyare put to one side and are moved from there in an automated fashioninto the removal region 31. The workpieces are now removed after oneanother by the first gripper 34 until the container is 100% empty. Theemptied container is thereupon moved to the channeling out path and ischanneled out from there.

In this respect, a safety detection of the container interioradvantageously takes place again after the removal of the last workpieceto ensure that actually no more workpieces remain in the container. Iftherefore the control only identifies a single workpiece on a detectionprocedure and if the gripper was controlled accordingly to remove it, afurther detection procedure is nevertheless initiated. Only in this waycan it be ensured that the last detected workpiece was also actuallyremoved.

Furthermore, the embodiment shown in FIG. 11 shows a second intermediatestation 65 on which the workpieces removed from the first intermediatestation by the gripper 41 are placed to be picked again. The placing onthe second intermediate station in this respect takes place in a definedposition, with the placing serving to be able to pick more accurately onthe picking up and/or to be able to vary the orientation of theworkpiece at the gripper. The second intermediate station canfurthermore also serve as a buffer store.

An embodiment of such an intermediate station 65 is shown in FIG. 12.The intermediate station has at least one receiver 67 for the workpiecesinto which the workpiece can be placed in a defined position andorientation. In the embodiment, in this respect, a plurality of suchreceivers 67 are arranged next to one another so that the intermediatestation also serves as a buffer store.

The receivers 67 have a compensation apparatus 70 which also allows aplacing of the workpieces in the receiver 67 with a certain positionaloffset in that the receiver is moved by the contact with the workpieceto be placed down. For this purpose, the receiver 67 has receiver steps72 against which a badly positioned workpiece first abuts and in sodoing causes a movement of the receiver by which the workpiece can beplaced in the receiver.

The receiver 67 thus allows a placing of workpieces in a definedpositional region and thus in particular also allows the placing ofworkpieces not exactly picked in a desired position.

The compensation unit 70 can be fixed on the intermediate station sothat the receiver and thus the workpiece is arranged in a defineddesired position for the removal. The removal of the workpiece canhereby take place with a greater accuracy.

The receivers 67 are displaceable on rails 69 at the intermediatestation. In this respect, the receivers can be displaced from a loadingposition, in which the compensation unit allows a movement of thereceivers 67, into a removal position in which the compensation unit isfixed. Abutments 71 are provided for this purpose into which thereceiver 67 is traveled and which fix the receiver in a definedposition.

The placing and the removal of workpieces onto the second intermediatestation 65 in this respect in each case advantageously takes place bymechanical grippers since they have a relatively high picking accuracyby which the workpieces can be placed in a defined manner in thereceivers and can be picked up again with a higher accuracy.

The picking of the workpieces on the second intermediate station in thisrespect takes place without a previous detection of the workpieces inthat the grippers are traveled to the known removal position of thereceiver.

The receivers are furthermore designed so that the workpieces can bepicked from two different directions. In the embodiment, the workpiecesin this respect have cut-outs into which the fingers of a finger gripperengage. The receivers are designed in this respect such that thecut-outs are accessible from two sides in the workpieces when aworkpiece is arranged in the receiver. The orientation of the workpieceat the gripper can hereby be reversed in that the workpiece is pickedfrom one side on the placing down, but from the other side on thepicking up.

In this respect, the placing down and the picking up can take place bythe same gripper. In the embodiment shown in FIG. 11, however, twoseparate grippers are used.

In the embodiment of an apparatus in accordance with the invention shownin FIG. 13, which is likewise based on the embodiment shown in FIG. 4, afurther embodiment for a second intermediate station 73 is now shown.This intermediate station also has at least one receiver 74 in whichworkpieces can be placed down in a defined manner. The receiver is inthis respect designed in exactly the same way as the receivers shown inFIG. 12.

The intermediate station shown in FIG. 13 in this respect has atransport belt by which the receiver 74, which is at least movable to acertain extent on the transport belt, can be traveled toward abutmentsto fix it in its position. A compensation unit is also hereby providedwhich allows a placing down of the workpieces in the receiver 74 with acertain offset and which nevertheless moves the workpiece or thereceiver for removal into a defined position so that picking can againtake place with higher accuracy. Furthermore, picking can also takeplace here from both sides to change the orientation of the workpiece atthe gripper.

The intermediate station 73 shown in FIG. 13 is furthermore equippedwith a functional unit 75 which the workpieces run through on theintermediate station. The functional unit is in this respect ademagnetization station through which the workpieces are guided on theintermediate station.

In the embodiment shown in FIG. 13, the same mechanical gripper 41 is inthis respect used both for placing the workpieces on the intermediatestation 73 and for removing the workpieces.

Furthermore, a determination of the picking accuracy can take place withan apparatus for the automated handling of workpieces in accordance withthe present invention. It can in this respect in particular bedetermined whether and/or how much the position of a workpiece picked upat the gripper differs relative to the gripper from a predefined desiredpicking position or from a predefined desired picking position region.The process routing of the handling is advantageously then controlled independence on the result of such a picking accuracy determination.

In this respect, an embodiment of an apparatus in accordance with theinvention is shown in FIGS. 14 and 15 with which the picking accuracy isdetermined by traveling the gripper with the workpiece toward a separatemeasuring device 77. For this purpose, the gripper 41 is traveled into adefined position before the measuring device 77 when it has picked aworkpiece 78. The measuring device 77 then determines the position ofthe workpiece 78 and can thus determine the relative position betweenthe workpiece and the gripper from the known position of the gripper andthe position of the workpiece. A determination of the picking accuracyor of the position of the workpiece at the gripper is hereby possible.

In the embodiment, the separate measuring device 77 has laser sensors 79in this respect. In the embodiment, a three-point measurement is carriedout in this respect.

A determination of the picking accuracy can in particular be ofadvantage with mechanical grippers since they admittedly allow arelatively exact picking of the workpieces, but there are also degreesof freedom on picking here. If it is a finger gripper or a jaw gripper,the workpiece can usually be picked in different positions at least withrespect to the delivery direction of the gripper to the workpiece. Withthe finger gripper, this relates to the question how far the fingersengage into a corresponding receiver at the workpiece or how far thefingers engage around the workpiece.

In the embodiment of an apparatus in accordance with the invention shownin FIG. 14 which is based on the embodiment shown in FIG. 4, the pickingaccuracy of the gripper 41 which is used for removing the workpiecesfrom the first intermediate station is in this respect determined.Alternatively, however, the picking accuracy on the removal of aworkpiece from a second intermediate station could also be determined.

Alternatively to the separate measuring device which is shown in FIGS.14 and 15 and toward which the gripper can be traveled, a sensorarranged at the gripper itself can also be used for determining thepicking accuracy. An embodiment for such a sensor will be described inmore detail in the following.

The result of the determination of the picking accuracy can in thisrespect be used in different manners for controlling the apparatus.

On the one hand, it is possible that a picking error on the placing ofthe workpiece recognized in this determination is compensated by acorresponding control of the griper or of the gripping arm moving it.This substantially corresponds to a zero point adjustment of the gripperon placing which changed in dependence on a deviation of the workpiecefrom a desired picking position.

It is furthermore conceivable that poorly picked workpieces are placeddown again to be picked again. Such a procedure can in particular besensible when the picking accuracy lies outside a predefined permittedregion.

In this respect, the workpiece can be placed back on the transport belton the picking from an intermediate station with a transport belt suchas is shown in FIG. 4 or 14, for example, when the picking accuracyfalls below certain criteria. In an advantageous manner, the workpieceis in this respect placed onto the transport belt in a position fromwhere the workpiece again arrives in the removal region. The workpieceis in this respect advantageously again detected and then again pickedusing the data determined from this. In this respect, the probability ishigh that the workpiece can now be picked with sufficient accuracy.

In this respect, a combination of the two procedures is alsoconceivable. If the accuracy therefore lies outside a permitted region,the workpiece is placed back. Otherwise, the determined deviation from adesired picking position on the placing down of the workpiece iscompensated by a corresponding movement.

In FIG. 16, an embodiment of a gripper in accordance with the inventionwith a stabilizer element is shown. In the embodiment, it is in thisrespect a mechanical gripper with which the workpiece is picked. Toprevent positional changes of the workpiece at the gripper, while thegripper is moved, the stabilizer element 80 is traveled toward thepicked workpiece. The stabilizer element 80 has a stabilizer plate atwhich contact elements are provided for contacting the workpiece. Theadditional contact points thus provide a positional fixing of theworkpiece at the gripper.

In the embodiment the gripper is configured as a two-finger gripperhaving the two gripping fingers 50 which are introduced into cut-outs ofthe workpieces for picking. The two contact points established by thetwo gripping fingers 50, however, do not fix the workpiece in a clearposition with respect to the gripper so that only the further contactpoints of the stabilization element establish a defined position of theworkpiece at the gripper. The contact points of the stabilizer elementare in this respect advantageously arranged remote from line connectingthe two gripping fingers 50 in this respect.

In the embodiment, the stabilizer element 80 is arranged in the regionof the two gripping fingers and is attached around it. The stabilizerelement could, however, also be arranged in any other position at thegripper.

The design of the stabilizer element can again be recognized in thesectional view shown in FIG. 17. In this respect, the stabilizer plate81 can be recognized at which, for example, contact elements can bearranged in the region 82. The stabilizer plate 81 surrounds thegripping finger 50 in this respect in the form of a ring or of ahorse-shoe in the embodiment.

The stabilizer plate 81 is arranged at a cylinder 83 by which it can betraveled to the workpiece. The cylinder 83 is a pneumatic cylinder. Thestabilizer element can thus be traveled toward the workpiece whenpneumatic pressure is applied at the one side of the cylinder or can betraveled in when pressure is applied to the other side of the cylinder.

The end abutments 84 and 85 of the cylinder 83 are equipped with sensorswhich recognize whether the stabilizer element is located in one of itsend abutment regions. A determination of the picking accuracy is herebypossible since the moving-out distance of the stabilizer element dependson the position of the picked workpiece at the gripper.

If the stabilizer element is in this respect located in the active statein one of its end abutment regions, an insufficient picking accuracy isconcluded since the gripper was then either traveled too far into theworkpiece or not far enough. A more precise determination of the pickingaccuracy could naturally also take place by a measurement of thepush-out length of the cylinder 83.

Alternatively to the sensor arrangement integrated into the stabilizerelement 82 for determining the picking accuracy, a separate sensor wouldalso be conceivable which is arranged at the gripper. For example, inthis respect, a laser sensor could be used which is arranged at thegripper to determine the picking accuracy.

In FIG. 17, a compensation unit 49 can also be seen via which thegripper is fastened to a gripping arm.

In FIGS. 18 and 19, a first embodiment of such a compensation unit isshown in more detail. In this respect, a base element 90 is provided atwhich a compensation plate 91 is arranged. The compensation plate 91 isengaged around by holding elements 92 of the base element 90. A springarrangement 93 which presses the compensation plate 91 toward theholding regions 92 is arranged between the base element 90 and thecompensation plate 91. In the embodiment, in this respect, a pluralityof coil springs are provided which are arranged in corresponding springsleeves. However, any desired other embodiments of such a springarrangement are also conceivable.

The spring force of the spring arrangement is in this respect selectedsuch that the compensation plate 91 is held rigidly at the base unit 90in normal operation of the gripper. Only in the case of a collision ofthe gripper or of the workpiece arranged therein with an interferingedge or with another workpiece does the spring arrangement 93 allow arelative movement between the compensation plate 91 and the base element90. The forces exerted on the gripping arm are hereby limited. It can inparticular thus be prevented that the emergency stop of a robot used formoving the gripper or of a surface portal engages.

The force of the spring arrangement 93 can in this respect be set sothat the compensation element can be adapted to the correspondingpurpose. The setting of the spring force can in this respect inparticular take place in that the gripper is moved together with apicked up workpiece into a 90° position to the vertical so that thestatic load by the gripper and the workpiece on the compensation unit isat a maximum. In this position, the preload of the spring arrangement 93is set so that no deflection of the compensation unit takes place. It ishereby ensured that no deflection of the compensation unit takes placeindependently of the orientation of the gripper by the static forcesalone which are applied to the compensation unit by the gripper and apicked up workpiece. Optionally, the preload of the spring arrangement93 can in this respect still be increased by a certain value in orderalso to take account of dynamic loads, for example on the accelerationof the gripper or of the gripper arm.

The preload of the spring arrangement 93, however, has to be selected sothat the compensation unit triggers before the emergency stop of thegripper arm engages.

The first embodiment of a compensation unit in accordance with theinvention can in this respect, for example, be used together with amechanical gripper. The first embodiment of a compensation unit inaccordance with the invention can in this respect in particular be usedfor the second gripper which picks up the workpieces from theintermediate station. Furthermore, the first embodiment of thecompensation unit in accordance with the invention can also be used withthe third gripper which picks up the workpieces from the secondintermediate station.

The first embodiment of the compensation unit in accordance with theinvention in this respect has a spherical operation and in particularallows tilt compensation movements. The compensation unit in thisrespect advantageously allows a maximum compensation angle between 2°and 10°, in particular between 4° and 6°.

In this respect, guide elements are furthermore provided which prevent arotation of the compensation plate 91 with respect to the base element90. In the embodiment, guide pins engage for this purpose laterally incorresponding cut-outs of the compensation plate 91.

The compensation plate is in this respect round in the embodiment andhas rounded edges to allow a pivot movement around any desired axes.

Contact sensors 94 are furthermore arranged in the region of the holdingregions 92. They monitor whether the compensation plate 91 lies on theholding regions or was deflected. Collisions of the gripper can herebybe detected. The sensors 94 in the embodiment are inductive sensors. Inthe embodiment, in this respect, a plurality of sensors are provided sothat information can be obtained on the direction of the deflection ofthe compensation plate 91. Four sensors are in particular provided inthis respect.

The data obtained from the sensors can in this respect be used forcontrolling the gripper as follows: In normal operation, thecompensation unit does not deflect so that the gripper adopts a definedposition with respect to the gripping arm which remains unaffected bythe compensation unit. On a collision, the compensation unit, however,deflects, which is recognized by the sensors 94.

In this case, the control still allows a certain adjustment path of thegripping arm which is, however, smaller than the compensation path ofthe compensation unit.

If the movement of the gripping arm, however, exceeds this permittedadjustment path after the recognition of a collision, the pickingprocedure is stopped and the gripper is traveled back into a zeroposition. A picking procedure is thereupon started again in that theworkpieces are first detected and then a new picking movement isinitiated. The compensation unit in this respect protects against anemergency stop of the robot, which could only be cancelled againmanually.

In FIGS. 20 to 22, a second embodiment of a compensation unit inaccordance with the invention is shown. This compensation unit combinesa compensation unit with a spherical operation as is shown in FIGS. 18and 19 with a compensation unit with a linear operation in order thus toincrease the compensation path.

The total compensation unit 200 in this respect first comprises thespherical compensation part 201 which substantially corresponds indesign to the first embodiment of a compensation unit and combines it inseries with a second compensation part 202 which has a linear operation.

As can in particular be recognized well in FIG. 21, the sphericallyoperating compensation part 201 has the same mechanical design as thefirst embodiment of a compensation unit in accordance with theinvention, with the same reference numerals also being used for thispurpose. In this respect, a base element 90 is in particular provided atwhich the compensation plate 91 is arranged and is engaged around byholding elements 92 of the base element 90. A spring arrangement 93which presses the compensation plate 91 toward the holding regions 92 isarranged between the base element 90 and the compensation plate 91. Inthis respect, adjustment elements 97 are shown via which the preload ofthe spring arrangement 93 can be changed.

The design of the spherically operating compensation part 201 differsfrom the first embodiment of a compensation unit in accordance with theinvention only with respect to the sensor which is used for detecting acompensation movement. Unlike in the first embodiment, in this respect alight barrier is used having a transmitter 99 a and a receiver 99 bwhose light path runs through a bore 98 through the compensation plate91. If the compensation plate 91 is deflected in this respect, itinterrupts the light path of the light barrier.

The sensor thus recognizes in accordance with the invention thecompensation movement of the spherically operating compensation part201. No sensor is in contrast provided for the linearly operatingcompensation part 202.

The linearly operating compensation part 202 is in this respect arrangedbetween the base element 90 and the gripping arm. In this respect,fastening regions 203 at which bars 204 are arranged are provided in thecorner regions of the base element 90. The bars 204 are guided in alinearly displaceable manner in guides 205 which are arranged at a plate210. The plate 210 is then in turn connected to the end of the grippingarm. The movement of the bars 204 in the guides 205 takes place againstthe preload of a spring arrangement 206 which can be set via adjustmentelements 207.

The two-stage compensation unit in accordance with the present inventionis combined in the embodiment with a magnetic gripper 211 and can becoupled via a cropped gripping arm extension 212 to a gripping arm, inparticular to a robot arm. For this purpose, the gripping arm extension212 has a coupling surface 213 with which it can be coupled to the lastpivot joint of a robot arm.

The two compensation parts 201 and 202 of the compensation unit areconfigured in this respect such that the spherically operatingcompensation unit 201 deflects first and only then the linearlyoperating compensation unit 202. The linearly working compensation unit202 can in this respect have a compensation path between 1.5 and 5 cm,preferably between 2 and 3 cm. This compensation path allows themovement of the gripper to be braked in good time in the event of acollision before the total compensation path of the compensation unithas been utilized.

The preload of the spring units of the second embodiment of acompensation unit could be set in the same manner as the spring load inthe first embodiment of a compensation element in accordance with theinvention. In this respect, the preload of the spring unit 93 could inparticular be set so that it also takes up the static loads from thegriper and a workpiece hung on with a gripper pivoted to the side by 90°without deflecting the compensation unit. The preload of the spring unit206 of the linear part of the compensation unit were then be setcorrespondingly greater. In this respect, however, it must be taken intoaccount that the preloads of the two parts of the compensation unit haveto be set so that the compensation units still deflect beneath themaximum load limit of the robot arm. This is in particular difficult torealize with very heavy grippers or very heavy workpieces in which thestatic load already lies close to the maximum load of the gripping arm.

Alternatively, the preload of the spherical part of the compensationunit can therefore be set such that it only takes up the static load bythe magnetic gripper when it is located in a position directed 90° tothe side, but already deflects with a workpiece hung on in thisposition.

The present invention in this respect makes use of the fact that thegripper with the picked up workpiece can be moved immediately after thepicking up into a travel position in which the gripping surface facesdownward so that the static loads by the gripper and the workpiece aretaken up by the compensation unit without it being deflected. A slantedorientation of the gripper is, in contrast, only necessary on thetraveling toward the workpiece to bring the gripping surface of thegripper into coverage with the main surface or with the engagementpoints of the workpiece.

In this respect, the gripper advantageously travels perpendicular to thegripping surface toward the workpiece, picks it and is then traveledback in the opposite direction again together with the workpiece. Inthis respect, the signal of the sensor of the compensation unit is notconsidered for a certain path distance on the moving back in order notto evaluate a deflection of the compensation unit solely due to thestatic load by the workpiece hung on and/or due to dynamic loads due tothe traveling of the gripping arm erroneously as a collision. Duringthis path distance, the gripper is simultaneously traveled into a travelposition in which the gripping surface and thus the tool face verticallydownwardly and thus do not act against the spring elements of thecompensation unit.

If the gripper is moved back by a certain distance and if it was pivotedin the travel position, the signal of the sensor of the compensationunit is again used to detect collisions of the gripper or of theworkpiece with interference edges.

On the traveling of the gripper toward a workpiece, the signal of thesensor of the compensation unit can moreover be utilized to detect thecontact of the gripper with the workpiece. The gripper is in thisrespect traveled slowly to the workpiece until the compensation unitdeflects.

Independently of the exact embodiment of the compensation unit, in thisrespect in accordance with the present invention, work can be carriedout with different travel speeds for the gripping arm depending on theregion in which the gripper is located. The gripping arm can in thisrespect be moved in fast motion, i.e. at a high speed, in a region inwhich the gripper is located outside the container and thus no collisionwith interfering edges is to be feared. If the gripper is, in contrast,located in the region of the container so that collisions have to beanticipated, it preferably works at a second, lower speed. The speed isin this respect selected so that the gripper can be stopped on acollision with an interference edge before the compensation path of thecompensation unit is completely used up and the compensation unit doesnot permit any further compensation movement. In the near region to theworkpiece to be picked up, the gripper is furthermore preferablytraveled at a third, even lower speed. This still allows a certaintravel path of the gripper or gripping arm on the detection of acollision before its movement has to be stopped.

Embodiments of the methods in accordance with the present invention willnow be presented in more detail again with reference to flowcharts. Theycan preferably be carried out using apparatus such as were describedabove.

FIG. 32 in this respect shows the routine of the detection of theworkpieces in an embodiment of the present invention, and indeed bothfor the case that workpieces randomly arranged in a container aredetected and workpieces randomly arranged on an intermediate station aredetected.

In step 100, the system is located in a starting state. The gripper forpicking the workpieces can in particular be arranged outside thedetection region in this starting state. The gripper can for thispurpose either be set down in a parking position or can carry outactions in a region outside the detection region such as, for example,placing down an already picked workpiece.

In step 101 or 106, a measurement now takes place by the sensors of theobject recognition device. For this purpose, in particular a 3D laserscanner can be used in the embodiment. With the 3D laser scanner used inthe embodiment for detecting the workpieces in the container, the 3Dlaser scanner is first traveled into a measuring position above thecontainer from where the scanner is pivoted over the detection region.Alternatively, a detection during the horizontal travel movement of the3D laser scanner would also be possible. On the detection of theworkpieces on the intermediate station in accordance with step 106, thesensor is, in contrast, fixedly installed, with it being pivoted bypivoting over the detection region.

Alternatively to the use of a 3D laser scanner, a camera system or acombination of a camera system and a laser scanner could also be used. A2D or 2.5D detection by means of a camera can in particular also beconsidered in this respect.

In step 102, the data are now evaluated and the workpieces identified.

The identified workpieces are evaluated with regard to their positionstoward one another. It is in particular determined in this respect whichworkpieces lie highest and which workpieces are at least partly coveredby other workpieces. A selection is hereby prepared for the decisionwhich part is suitable for picking.

In step 103, a decision is now made as to which part is to be picked inthe next step. If this is not possible using the existing data, adetection can be carried out again in a new cycle, for which purpose thesystem moves back into the starting state in step 107.

If, in contrast, a workpiece was selected, a track planning for thegripper takes place in step 104. The determined parameters of the partto be picked which describe the position and spatial arrangement of thepart are used as the basis for the track planning. The system in thisrespect knows its current location and the target coordinates. The path,the so-called track, can then be calculated with the aid of thedetermined spatial data.

In this respect, a collision identification also advantageously takesplace in which the gripper and the container are represented bygeometrical data and the planned track is simulated in order thus todetermine possible collisions in advance and to preclude them in thetrack planning by determining an alternative path.

In step 105, the controlling of the gripper and the picking of aworkpiece take place using the data thus calculated.

Before now the different picking strategies in accordance with theinvention are shown next to one another with reference to FIGS. 24 and25, the possibilities for the design of an apparatus in accordance withthe invention should be shown again in overview by which thecorresponding strategies can be implemented.

An apparatus in accordance with the present invention can comprise twogrippers. A first gripper is used to roughly pick the parts from thebin. A second gripper is provided for the precise picking andsingularization on an intermediate station which can in particular beequipped with a transport belt. The second gripper places the workpieceson a further intermediate station or on a target receiver for ameasurement treatment or work treatment of the workpieces. Which type ofgripper is use depends on the geometry, the design, the size and/or theweight of the workpieces to be picked and/or on the number of grippingzones and on the geometry and the design of the gripping zone.

The workpieces can, however, possibly catch with one another, lie aboveone another or also remain stuck. They can have gripping zones which arenot sufficient for a direct picking from the bin since they are notsufficiently accessible in certain positions which they can adopt with aplurality of parts in the bin. If the parts in this respect possiblyonly have a specific gripping zone, a targeted, direct picking with amechanical gripper proves not to be sufficiently reliable and ismoreover slow and prone to problems.

In a preferred case, the first gripper is therefore a magnetic gripperand the second gripper is a mechanical gripper.

The use of a magnetic gripper for the pick in the bin or the containerhas the advantage that no exact picking in a precise gripping zone isrequired. Furthermore, with a magnetic gripper, a picking at differentgripping points of a workpiece is usually possible. A picking at thehighest point of the workpiece is also in particular usually possible.Furthermore, with a magnetic gripper, a simultaneous picking of aplurality of parts is possible to place them on the intermediatestation. In accordance with the invention, a fast and one hundredpercent emptying of the bin is thus possible by the use of a magneticgripper.

A mechanical gripper has the advantage that the part can be pickedprecisely in a gripping zone so that the workpiece can subsequently beplaced individually in a defined position on or in a receiving station.The receiving station can in this respect be the receiving station of afurther intermediate station or the target receiver of a measurementstation or processing station. The workpiece can equally be placed on anintermediate station which serves as a buffer station or as ademagnetization station or measurement station.

The preferred case of a combination of a magnetic first gripper and amechanical second gripper is in particular used with workpieces having aposition-orientated gripping zone and/or an asymmetrical, symmetrical orrotationally symmetrical contour with a corresponding size and weight. Amagnetic gripper can in this respect naturally only be used when theworkpiece can be picked by a magnetic gripper, that is comprises metal,for example.

In this respect, the magnetic gripper places the workpieces on anintermediate station, where they are detected again so that they can nowbe picked directly by the mechanical gripper and can then be placed ontoa processing station, measurement device or a transport belt.

The following further combinations for the configuration of the firstand second grippers are likewise conceivable: mechanical/mechanical,pneumatic/mechanical, mechanical/pneumatic, pneumatic/pneumatic andmagnetic/pneumatic. Any desired other combinations of mechanical and/orpneumatic and/or magnetic grippers are also conceivable.

The grippers can in this respect each be moved either by a robot arm ora linear portal or a surface portal. Optionally, the respective gripperscan be combined with a compensation unit and/or with a force torquesensor depending on which strategies are to be used in picking. Thecompensation unit in this respect improves the system security in thatit prevents the necessity of an operator intervention on collisions.

The intermediate station has a transport belt which transports theworkpieces from the placing region into a removal region. In thisrespect, the placed down parts are conveyed via a workpiece slide to thetransport belt. So that the parts placed down by the magnetic grippercome to lie as ideally as possible on the transport belt, the transportbelt is bounded by slanted metal sheets which allow workpieces slidingonto the margin of the transport belt to slide back onto the belt. Atthe same time, a flap which can be moved by the workpieces, inparticular a pivotable metal sheet or a transverse bar, can be installedabove the transport belt so that parts lying above one another can stillbe singularized or parts not positioned correctly tilt over. Theworkpieces can hereby be better detected by the scanner or camera andcan be picked better.

A design with only one gripper which picks first in the container,places the workpiece on an intermediate station and then picks theworkpiece again for singularization would be alternatively conceivable.The first gripper would thus also be used for removing the workpiecefrom the intermediate station and for placing it on a furtherintermediate station or the target receiver.

The invention in this respect comprises the following methods which canin particular be carried out in the operation of an apparatus inaccordance with the invention:

Sorting Out Workpieces:

If the first gripper is combined with a force tongue sensor, a selectioncan already be carried out at this point by weight of the workpieces.Workpieces which lie outside a specific limit with respect to weight canin particular be sorted out. They can in particular be sorted out into asorting out container.

A sorting out by the first gripper is also possible in that workpieceswhich are recognized as lying outside a predefined specification ondetection are picked up and are placed in a sorting out containerinstead of on the intermediate station.

Workpieces which are detected on the intermediate station and which lieoutside a predefined specification can be sorted out. This can inparticular take place by a further transport of such workpieces into asorting out container at the end of the transport belt.

It is equally conceivable to hold a just picked part at a measurementdevice where e.g. geometries, surfaces (for example a lacquering) and/ormarkings (e.g. by codes) can be measured and/or inspected. If thismeasurement indicates that a part lies within a predefinedspecification, the picked part is placed down normally, e.g. on theintermediate station or on a target receiver. If it is outside thespecification, it is sorted out.

Prevention of System Stops:

A system stop can be prevented by picking with an offset at which thegripper slightly misses the ideal picking position. In this case, thegripper travels back around 25 mm and starts to travel again in order topick more precisely this time.

Furthermore, it can be recognized via a force torque sensor when toomany parts were picked at once. In particular when hereby the maximumload of the robot could be exceeded, the load can be reduced by adropping of the workpieces back into the container. The parts remainingat the gripper can then be unloaded at the intermediate station.

If the situation arises at the intermediate station that the objectrecognition device cannot detect the part exactly since the parts e.g.lie above one another and cannot be detected exactly or that a pickingis not possible or only takes place with insufficient accuracy, thefollowing strategies can be used:

On the one hand, a further, lower-lying transport belt can be used onwhich the parts not picked travel on in order thus to adopt the requiredposition by falling over a stage. The workpiece thus has a second chanceand is again supplied to the transport belt for precise picking (Loop2). In this respect, e.g. with smaller parts which can catch with oneanother, provision can also be made that the transport path guided as acircuit has singularization devices which pulls the parts apart andhereby singularizes them. For this purpose, sheet metals or transversebars can, for example, be used which narrow the transport belt and/orbrush the workpieces.

If the parts are admittedly picked, but no exact picking takes place,this can be registered via a sensor. For this purpose, for example, apneumatic cylinder can be provided at the mechanical gripper. This notonly recognizes the gripping position within a necessary limit for asubsequently precise placing of the parts, but also has the consequenceof a stabilization of the part in picking. On a recognized inexactpicking, the second gripper can place the workpiece back onto a frontpart of the transport belt of the intermediate station. The part thusalso has a second chance for exact picking (Loop 1).

On picking a workpiece from a container, the above-named strategies canin particular be combined to form the routine shown in FIG. 24:

In this respect, the system is in a base state in step 110 in which thetrack calculated by the track planning is predefined for the gripper. Instep 111, the attempt of picking then takes place using the calculatedtrack planning.

If in step 112 more than one workpiece is picked, the further proceduredepends on whether this can be recognized by a sensor. If this is notthe case, the workpieces are simply unloaded onto the transport belt.Otherwise it is possible to carry out a measurement with respect toforce, weight, number or optics in step 113. A force torque sensor canin particular be used in this respect. Alternatively, a 3D laser or a 2Dcamera or a 2.5D camera can also be used here. A decision now takesplace by recognizing predefined limits whether too many parts werepicked up. If too many parts were picked up, a falling of all parts backinto the bin can take place either in step 114 by a switching off orreducing of the gripping force of the gripper. After this step 115, acompletely new picking procedure takes place, including detection of theparts. Alternatively, in step 117, a part regulation can take place bypartial reduction of the force of the gripper and thus partial droppingof the workpieces back into the bin. In step 119, a check can again bemade whether at least one part is hanging on. If such a part is hangingon, this can be unloaded on the intermediate station in step 120. If nopart is hanging on, a new picking cycle can be started directly.

If, in contrast, it is recognized in the measurement that only one partis hanging on, this can be unloaded directly. If it is recognized in themeasurement that no part at all was picked up, a new picking cycle canstart immediately.

It is shown in step 122 how it is possible to proceed if a centeredpicking is not possible. In this case, the gripper either searches forthe highest point of the selected part and grips at this point again instep 124 or it picks with an offset in step 123, i.e. it travels back byabout 25 mm from the part and then travels toward the part again.

Alternatively, such a decision can already take place when it isrecognized in the selection of the workpiece to be picked that none ofthe parts is centered in a pickable manner. In this case, a picking canalready be planned in the track planning with an offset at which thegripping surface and the main surface of the workpiece do not fullyoverlap or a picking at the highest point can be planned.

The system can deal with collisions as follows in this respect: If nocollision occurs, as in step 121, the workpieces can thus be unloaded onthe intermediate station. If, in contrast, in step 125, a collision isrecognized, for example, by a force torque sensor and/or a compensationunit, the control still allows a defined travel path. If this is alsoexceeded, the picking procedure is stopped and the system starts a newpicking cycle. If, in contrast, the collision in step 127 is onlyrecognized by the emergency stop function of the robot, this results ina system stop in step 128 which can only be cancelled again by anoperator intervention 129.

On the picking of a workpiece from the intermediate station, and inparticular from the transport belt of the intermediate station, thestrategies in accordance with the invention can in particular becombined to form the routine shown in FIG. 25:

First, in steps 130, a workpiece travels on the transport belt into therecognition region of the object recognition device and the transportbelt stops. Then the recognition is carried out, in particular ascanning by a 3D laser scanner. It can be pivotable or travelable in avertical or horizontal manner or can be arranged at a fixed positionabove the transport belt. Alternatively, a taking of an image can takeplace via a 2D, 2.5D or 3D camera. After the evaluation of the data andthe corresponding determination of a track for the gripper, as wasalready previously described, the picking then takes place in step 131.

The picking of more than one part in step 138 can trigger the sameprocedure as in the picking from a container. If in this respect amechanical gripper is used, only the possibility remains, however, ofdropping all parts in steps 140 and 141.

The procedure in the event of a collision in steps 148 or 144 is alsoidentical to the procedure on picking from a container.

On an inexact picking in step 143, a procedure can likewise be followingas was presented with respect to the corresponding steps in FIG. 23.These strategies can in particular be used when a magnetic gripper isused as the second gripper.

Furthermore, when the picking accuracy in step 134 is no longersufficient, the part can again be placed onto the front part of thetransport belt (Loop 1) so that the workpiece can again be detected andpicked.

If no recognition is possible or if no workpiece can be picked, theworkpiece can again be conveyed over a return path onto the transportbelt in a corresponding embodiment of the intermediate station so that arepeat chance for picking is given (Loop 2). Otherwise the workpiecewhich cannot be picked has to be traveled into a sorting out container.

The present invention makes possible a handling of the workpieces withfast cycle times, small error rates and a great accuracy in picking withthe above-presented apparatus and methods. In this respect, a highprocess security results by the avoidance of system downtimes whichwould require operator intervention. Furthermore, the present inventionallows a 100 percent emptying of the containers.

1. An apparatus for automated handling of workpieces, comprising anobject recognition device for detecting the workpieces; and a gripperarranged at a gripping arm for picking up the workpieces; and a controlfor evaluating data of the object recognition device, for track planningand for controlling the gripping arm and the gripper; and comprising acompensation unit which allows an evasion movement of the gripper,wherein the compensation unit only allows an evasion movement of thegripper on the exceeding of a predefined first load of the gripping armand remains rigid below the first load, wherein the first load is largerthan a load exerted on the gripping arm solely by the gripper and/or thepicked up workpieces.
 2. The apparatus in accordance with claim 1,wherein the compensation unit has a sensor arrangement which recognizesan evasion movement occurring due to a collision; wherein, upondetection of a collision a predefined travel path of the gripping arm isadvantageously still permitted, with the picking up procedure beingstopped and restarted on the exceeding of this permitted travel pathwhich corresponds to a second load of the gripping arm; and/or whereinthe control has an overload function which intervenes on the exceedingof a predefined third load of the gripping arm, with the third loadbeing larger than the first load and/or the second load.
 3. Theapparatus in accordance with claim 2, wherein the apparatus comprisestwo compensation units connected in series, with a first compensationunit advantageously being a compensation unit having a sphericalcompensation movement and a second compensation unit being acompensation unit having a linear compensation movement; and/or whereinthe two compensation units are advantageously preloaded via separatepreloading means and/or deflect at different loads of the gripping arm.4. The apparatus in accordance with claim 3, wherein the control isconfigured so that it changes an orientation of the gripper after thepicking up of a workpiece with a slanted gripper such that static forcesacting on the compensation unit by the gripper's own weight and a weightof the workpiece are reduced; wherein the gripper is in particulardirected downwardly into a travel position; wherein the change in theorientation advantageously takes place on a lifting of the workpiece;and/or wherein deflection of the compensation unit on lifting is notevaluated as a collision.
 5. An apparatus for automated removal ofworkpieces arranged in a container, comprising an object recognitiondevice for detecting the workpieces and a gripper arranged at a grippingarm for picking up and removing the workpieces from the container; and acontrol for evaluating data of the object recognition device, for trackplanning and for controlling the gripping arm and the gripper, whereinthe gripper is a magnetic and/or pneumatic gripper.
 6. The apparatus inaccordance with claim 5, comprising a force torque sensor arrangementfor measuring a load of the gripping arm, and/or wherein the controlreduces a gripping force of the gripper when it is in particularrecognized via data of the force torque sensor arrangement that morethan one workpiece was picked up, with a power of a gripperelectromagnet advantageously being reduced with a magnetic gripper. 7.(canceled)
 8. The apparatus in accordance with claim 6, wherein thegripper removes the workpieces from a container and advantageouslyplaces them on an intermediate station from where the workpieces arepositioned more accurately and/or are singularized via a positioningapparatus.
 9. A compensation unit, in particular for an apparatus inaccordance with claim 8, comprising a base unit and a compensation platewhich is engaged around by a holding region of the base unit and ispreloaded against the base unit and in particular the holding region viaa spring arrangement such that the compensation unit only allows anevasion movement between the base unit and the compensation plate on theexceeding of a predefined first load and remains rigid below the firstload, with one or more sensors advantageously being provided whichmonitor a placing of the compensation plate at the holding region, withthe one or more sensors advantageously being arranged in the holdingregion.
 10. The compensation unit in accordance with claim 9, whereinthe compensation plate is round and/or the margin of the compensationplate is rounded; and/or wherein the evasion movement between the baseunit and the compensation plate allows a spherical compensation movementand the compensation unit furthermore has a second compensation unitwhich allows a linear compensation movement, with the two compensationunits advantageously being preloaded via separate preloading meansand/or deflecting at different loads of the gripping arm; and/or whereinthe second compensation unit advantageously has one or more bars whichare linearly guided in a guide and are preloaded via a spring.
 11. Amethod of operating an apparatus for automated handling of workpieces,wherein the apparatus comprises: an object recognition device fordetecting the workpieces; and a gripper arranged at a gripping arm forpicking the workpieces; and a control for evaluating data of the objectrecognition device, for track planning and for controlling the grippingarm and the gripper; and a compensation unit which allows an evasionmovement of the gripper on the exceeding of a first load of the grippingarm, comprising selecting a first load is selected larger than theforces occurring in normal operation, wherein and the compensation unitremains rigid below the first load so that evasion movements of thegripper are prevented in normal operation.
 12. The method in accordancewith claim 11, wherein after the picking up of a workpiece with aslanted gripper, an orientation of the gripper is changed such thatstatic forces acting on the compensation unit by the gripper's ownweight and a weight of the workpiece are reduced; wherein the gripper isin particular directed downwardly into a travel position; wherein achange in the orientation advantageously takes place on a lifting of theworkpiece; and/or wherein deflection of the sensor on lifting is notevaluated as a collision.
 13. A method of operating an apparatus forautomated removal of workpieces arranged in a container, wherein theapparatus comprises: an object recognition device for detecting theworkpieces and a gripper arranged at a gripping arm for picking up andremoving the workpieces from the container; and a control for evaluatingdata of the object recognition device, for track planning and forcontrolling the gripping arm and the gripper, wherein the workpieces arepicked up magnetically and/or pneumatically.
 14. The method inaccordance with claim 13, wherein a load of the gripping arm ismeasured, with a gripping force of the gripper advantageously beingreduced when it is recognized that more than one workpiece was pickedup.
 15. (canceled)